ECSS Paris 2023: CP-PN05
INTRODUCTION: Relative Energy Deficiency in Sport (REDs) is a multi-factorial clinical condition associated with profound adverse long-term health and performance consequences. The predominate treatment for REDs is to increase energy availability (EA) via increasing energy intake (EI), with the athlete understanding their own EA equation playing a key role in their recovery. However, knowledge alone may not be enough to create the required behaviour modifications around increasing EI and/or improving EA across the day. Yet, there is a dearth of evidence regarding behaviour change to increase EA in those with, or at risk of REDs. This descriptive qualitative study investigated the acceptability of continuous glucose monitoring (CGM) in athletes clinically diagnosed with REDs, and how biofeedback from CGM may play a role in creating the required behaviour change for the recovery of REDs. METHODS: Females (n=8, 26.8 ± 6.4 years) with a diagnosis of REDs by an experienced medical specialist, participated in a seven-day trial whereby they wore an unblinded CGM sensor and were instructed to scan the sensor at least every eight hours. Participants were provided with only minimal information on what to expect in their glucose readings; no specific education was given as to how their glucose readings might reflect nutritional timing or choices. Participants also recorded their exercise data each day and their dietary intake for four days of the trial. A semi-structured interview guide was used to collect qualitative data to gain an understanding of the participants’ experience of wearing a CGM. Data were analysed using thematic analysis inductively for key themes. RESULTS: Two main themes emerged from the data. The first theme, “Acceptable but aware”, captured the participants’ experience of wearing the CGM during their recovery of REDs. Participants found it easy to use, predominately unobtrusive, and showed low to no anxiety with regards to the continuous access to their interstitial glucose levels. The second theme, “Engagement with the data”, portrayed the spectrum to which participants connected with the CGM data and identified the potential of CGM to impact nutrition behaviour in the recovery of REDs, particularly in response to exercise. CONCLUSION: The CGM appeared to provide an ‘objective permission’ to some participants to change their nutritional intake behaviours. This was predominately regarding fuelling before training, having linked their subjective feelings to the objective metrics on the CGM. However, there is a clear need to ensure individuals understand the CGM data, particularly around exercise, to be able to make meaningful change. CGMs do not appear to create anxiety in those diagnosed with REDs. With an accompanying education, CGM may have a potential role in creating behaviour change with regards to nutrition around exercise.
Read CV Penny Matkin-HusseyECSS Paris 2023: CP-PN05
INTRODUCTION: Bariatric surgery (BS) is highly effective for weight loss, but up to 50% of individuals regain weight within five years, largely due to reduced resting metabolic rate (RMR) linked to fat-free mass (FFM) loss. Changes in liver and kidney volume, highly metabolic organs, may explain RMR changes after BS. This study examined the effect of BS-induced weight loss on RMR and its association with highly metabolic organs. METHODS: Fifty-eight candidates (39.2±10.7y, 114.3±17.5kg, 41.7±4.4kg/m2) for BS were enrolled in a six-month open-label randomized controlled trial. Participants were randomly assigned to standard care (control, n=16), aerobic (n=15), strength (n=13), or combined exercise training (n=14) for 26 weeks of intervention. Training sessions were supervised online, and gradually increased to 60 minutes per session, three times a week. From week 5 each group participated in a specific progressive training regimen. Pre- and post-intervention RMR was measured by indirect calorimetry, body composition (FFM and fat mass) by dual-energy X-ray, and highly metabolic organs volume using 3-tesla magnetic resonance imaging (MRI). RESULTS: Forty-seven participants completed the 6-month intervention (81%). Participants in the exercise training groups (n=39) significantly increased their physical activity (PA) level by 79.8±90.8%. Significant (p<0.01) reductions were observed in body weight (-31.1±8.7 kg), FFM (-6.61± 2.6 kg), fat mass (-24.4±7.4 kg), kidney volumes (-35.1±25.2 cm3), liver volume (-384±250 cm3) and absolute-RMR (-397± 264kcal/day), all similar between the study groups. However, a significant metabolic adaptation of 368±234 kcal/day was observed following BS-induced weight loss regardless of the type and load of PA. The metabolic adaptation was significantly correlated with liver volume changes (B=0.379, p=0.005) contributing 36% to the observed metabolic adaptation. CONCLUSION: Our study provides the first evidence that metabolic adaptation in bariatric patients is significantly mediated by changes in liver volume, highlighting its critical role in influencing RMR. Further research is needed to validate these findings and determine their relevance for personalized weight management strategies post-bariatric surgery.
Read CV Lior FriedmanECSS Paris 2023: CP-PN05
INTRODUCTION: Energy utilization in skeletal muscle during contraction depends on muscle fiber type. Slow twitch fibers have higher fat oxidation capacity, while fast-twitch fibers are greater glycolytic metabolism. Previous studies have shown fat oxidation during low-intensity exercise increases after overnight fast, a phenomenon linked to changes in central nervous system (CNS) that enhance hormone secretion promoting lipid breakdown. Since muscle fibers are innervated by motor neurons, fast-induced changes in CNS also alter motor unit activation properties. We hypothesized that during low-intensity exercise after an overnight fast, the activity of motor units (MUs) with lower recruitment thresholds, which have muscle fibers with higher fat oxidation capacity, is enhanced. The present study aimed to investigate the effects of overnight fast on motor unit activation properties and its recruitment threshold dependency. METHODS: Eighteen adults participated in this study. After an overnight fast, participants performed measurements in the morning under two conditions in a double-blind, randomized controlled design. In non-intake condition (NIN), participants had a jelly containing 0 kcal and intake condition (IN), they had a jelly containing about 450 kcal. Two conditions were provided on separated days for each participant. On each day, respiratory exchange ratio (RER) during knee extension-flexion exercise at about 20% of VO2peak, maximal voluntary contraction (MVC) strength of knee extension, high-density surface electromyography (HDsEMG) from the vastus lateralis at 30% of MVC, and evoked twitch torque of knee extensors were measured. HDsEMG signals were decomposed into individual motor unit action potentials, and motor unit firing rate (MUFR) and recruitment thresholds (MURT) were calculated. Only MUs tracked between two days/conditions were analyzed. Shapiro–Wilk tests were performed to check the normality of all variables, followed by paired t-test or Wilcoxon signed-rank test. To investigate threshold-dependent changes in MU between conditions, Spearmans rank correlation analysis was performed on the changes in MUFR and MURT (NIN-IN) and MURT. RESULTS: RER was significantly lower in NIN than that in IN (p<0.01). There were no significant differences in MVC strength and evoked twitch torque between two conditions. A total of 116 MUs were tracked and analyzed. MUFR and MURT were significantly lower in NI than that in IN (p=0.03, p=0.02). The change in MUFR from NIN to IN and MURT was not significantly correlated (p > 0.05), but the change in MURT from NIN to IN and MURT were significantly correlated (ρ=0.28, p<0.01). CONCLUSION: The present study showed overnight fast with no energy intake enhanced fat oxidation during low-intensity exercise in the morning and enhancement of MUs recruitment with relatively lower recruitment threshold. Our results suggest alterations in energy metabolism induced by overnight fast is accompanied with changes in motor unit activation properties.
Read CV Kaito IgawaECSS Paris 2023: CP-PN05